One problem with the stock springs Mike, is not so much their older design (though that's part of it) but it's their actual age.
Springs sag a bit, but they also "take a set" in some cases. That's where one leaf tip rubs on the underside of the next leaf up and makes a wear line where things bind up. Once the springs sag down a bit, that line that used to be out past the normal ride-height setting is now right at the tip of the leaf. Locking things up until enough pressure is exerted.
This action does not stop the spring from flexing, but by resisting that initial movement makes for an extremely harsh ride.
Also, old rubber bushings can be worn out and no longer isolating things like they once did. And if the spring has slid over to one side or the other, it's now in metal-to-metal contact with the spring perches.
And for the most part, old shocks suck!
So while you can refurbish old stuff to work better than they have in 30 years, new is usually better.
I'm just not sure quite how best to set up a stock height truck anymore. Most of my experience is with lifted Broncos, so there is more data on how to soften (or make less harsh) the ride.
New shocks are key, but springs and shocks work together. New springs are decades better than the old, but even the new ones are made to carry reasonable loads so are not exactly squishy and spongy on the road. It's a Utility Vehicle after all, so most parts are made to do a certain number of things.
For lifted springs which mostly sit a bit high on empty or light stock-ish Broncos, I'm not sure just how our stock height replacements (or those of any other vendors) will sit. If high, then you're in business because you can remove one or more leaves and not only drop your Bronco down to the level/stance that you want, but at the same time soften up the ride even more.
Replacing the bushings helps too. Even polyurethane works well to give a more linear feel, but ultimately rubber still gives the best isolation. I'd like to see big squishy rubber bushings, pads of some kind between the spring perch and mounting plate with the leaf pack, and bigger bushings on the shocks. Then add some coil pads to the front springs and I bet there would be a notable improvement in perceived ride quality just from the road noise isolation.
If your old original C-bushings are worn out enough, you might even be feeling/hearing a lot more road noise than originally too. Loss of rubber insulators leaves metal-to-metal contact which is never good.
Lots of stuff you can do. I'm sure others will chime in with their experiences.
Paul